This invention relates to a moisture-curing sealing and adhesive compound based on a fully synthetic polymer, to its production and to its use.
Polyurethane-based moisture-curing sealing compounds are well known to the expert, for example from DE 37 26 547 and DE 39 43 090. According to these documents, they consist essentially of isocyanate-terminated polyurethane prepolymers. The non-sag behavior of jointing compounds was achieved by the addition of fine-particle solids--also referred to as fillers. In general, these fine-particle solids make a significant contribution towards ensuring that the sealing compound retains the necessary internal cohesion after application to stop it from running or bulging downwards from vertical joints. The additives or fillers mentioned may be divided into pigments and thixotropicizing fillers, also referred in short as thixotropic agents. In the case of jointing compounds based on polyurethane prepolymers, these thixotropic agents have to meet additional requirements. For example, there should be no unwanted reactions with the isocyanate groups. Accordingly, the thixotropic agents mainly used are swellable polymer powders, for example polyacrylonitrile, polyurethane, polyvinyl chloride, polyacrylates, polyvinyl alcohols, polyvinyl acetates and the corresponding copolymers. Particularly good results can be obtained with fine-particle polyvinyl chloride powder.
The properties of polyurethane jointing compounds can be further improved by adding other components to the polymer powder used as thixotropic agent. These other components are substances which belong to the category of plasticizers or swelling agents and swelling aids used for plastics. The optimal composition of the prepolymer/polymer powder/plasticizer/swelling aid systems has to be determined in each case. For example, neither the plasticizer nor the swelling aid should react with the isocyanate groups of the prepolymer. Accordingly, plasticizers from the class of phthalic acid esters are suitable, for example, for polyvinyl chloride powder as the thixotropic agent. Examples of suitable compounds from this class are dioctyl phthalate, dibutyl phthalate and benzyl butyl phthalate. Other classes of compounds which have the required properties are chloroparaffins, alkyl sulfonic acid esters, for example of phenols or cresols, and fatty acid esters. Plasticizers based on alkyl sulfonic acid esters and polyvinyl chloride are particularly preferred as the swellable polymer powder.
Although satisfactory non-sag behavior is generally achieved with these known agents, it could be improved in certain cases, for example in the case of wide joints or at high temperatures. In addition, it is desirable for environmental reasons completely to replace PVC.
In the case of adhesives, too, there are applications where the form in which the adhesive is applied should remain intact, for example in bonding in bead form on vertical walls or in the application of floor adhesives with a serrated spatula.
Accordingly, the problem addressed by the present invention was largely to avoid these disadvantages and to improve the non-sag behaviour of sealing and adhesive compounds without affecting other processing and performance properties.